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The future of BMW tuning is going to be based around turbo motors. The decision was made, so time to get comfortable with it. Two motors that will be at the heart of BMW tuning for some time to come will be the N63 4.4 liter V8 and the S63 which is the M version based on it. These motors will be powering the vast majority of M cars as well as the higher end BMW's for some time to come. With the F10 M5 set to hit interest in tuning this powerplant will only grow.

What are they?

The BMW N63 and S63 are both twin turbo and direct injected V8's. They are different from traditional turbo V8's in the sense that the intake and exhaust systems are reversed. By designing the intake and exhaust this way BMW is able to put the turbos in the V, or valley, of the motor on top instead of the traditional location which would have turbos at the bottom off the exhaust manifold. The advantage is that the exhaust gas leaves the head traveling a very short distance to reach the turbo. BMW engineers have often prided themselves on the response of their motors and with this type of design even when going to turbo motors they are able to provide very little lag and strong response from low RPM. Not to mention, top mount turbos are just flat out cool.

How are they different?

The S63 is based on the N63 but there are some very significant differences between the two motors. The main difference being that the S63 uses a pulse tuned, cross engine exhaust manifold. That sounds cool, but what does it mean? It means that each turbo gets its exhaust flow from 4 exhaust pulses but also from opposite cylinder banks. This exhaust gas is fed into twin-scroll turbos which means there are two passages for the exhaust gases in the turbos. The N63 on the other hand uses single scroll turbos which means one passage for the exhaust gases. It is this pulse tuned exhaust manifold as well as the twin-scroll turbos that is major difference in the architecture of the S63 vs. the N63.

BMW released the graphics above to illustrate what is taking place. By using this manifold with the twin scroll setup BMW is able to keep constant exhaust pulses flowing to the turbos at every 180 degree rotation. The N63 on the hand will have uneven exhaust pulses as it is fed by only one bank of cylinders instead of a cross-engine setup. This is a significant difference that shows BMW innovation in turbo development.

Any other differences?

Yes. The exhaust camshafts on the S63 are different, designed for higher lift. The S63 has a different cooling system using a belt-driven mechanical pump. An additional oil cooler is used in it that is mounted below the radiator as well as a larger engine oil cooler. The water to air intercoolers on the S63 are larger than those on the N63. The transmission fluid cooler used is also larger. The turbo bearings receive a separate cooling circuit on the S63. The intake setup is slightly different as well but this is more to meet pedestrian crash regulations than a design difference for performance.

The redline on the two motors is slightly different with the N63 set at 6500 whereas the S63 revs to 6800 rpm. In the upcoming F10 M5, it is likely the cam profiles in the S63 will be slightly different from the X5 and X6 M as the photos of the tachometer have shown a redline in the low 7000 range. The final major difference is that the compression ratios between the two are not the same also leading to speculation that the the S63 pistons may be stronger. The N63 compression is at 10.0:1 while the S63 is at 9.3:1. Why the compression difference? The S63 runs more boost with 17.4 psi peak vs. the N63 hitting 11.6 psi of maximum boost pressure. Other than these differences, the motors are the same with identical bore/stroke, valve sizes, and engine blocks.

Can I just add the S63 turbos, manifold, and other parts to my N63?

Maybe. Wish I had a better answer but that is where we are currently at with these platforms. Sure, you can order the parts as they are available from dealers but it is not quite so simple as just bolting them on. Yes, physically, you will have no issues matching them up. The problem would be the tuning. I can tell you there currently are tuners trying to do exactly this. Have they been successful? Well, the jury is still out on that as the hurdle seems to be the tuning. What is more likely is that upgrades that are currently in the works will apply to both the S63 and the N63. Since these upgrades will be more efficient than the factory parts anyway it will make the most sense to simply skip trying to mimic an S63 and go big. One of the reasons these motors will be so much fun to tune and will get so much attention is that with having the same basic architecture most if not all of the hardware will apply. The wildcard as always is the tuning but we expect that to be figured out especially with how much competition there will be in this sector.

What is the power difference between the two?

Well, in stock form the N63 is rated at 400 horsepower and the S63 is rated at 555 horsepower. The reality of it is that the motors are fairly close to one another in stock form, at least closer than the crank ratings from BMW would have you believe. The N63's higher compression likely plays a role in that allowing more horsepower per psi. Below you will see a dyno of a stock X6 M vs. a stock X6 50i. The cars actually belong to the same owner and the fuel is 91 octane and as luck would have it are from the same gas station. You will notice the peak horsepower difference is only 60 all wheel hp and the torque difference is just under 30 pound feet. The torque curves from 2750 to about 5000 rpm mirror each other pretty closely.

What happens at 5000 rpm though is the N63 falls off a cliff. The S63 does not look pretty either but the turbos show greater sustainability up top not only due to their size but also due to being fed with more exhaust pulses. Look at the large area under the curve from about 5000 to 6500 rpm for the S63. The N63 really stands to benefit up top from some larger turbos and that higher lift exhaust cam. To be perfectly honest, compared to the table top flat torque curves across the range of BMW naturally aspirated jewels like the S65 or S85, these curves look embarassing for a company like BMW that set such a high standard previously. Are turbos letting them be lazy? Clearly, these are all about the down low torque and not the top end although the S63 is able to shift its peak power to the right considerably compared to the N63. We have heard some preliminary details on the S63 in the M5 and it should have a powerband slightly more conducive to the top end we have grown accustomed to in M5's previously although it will not be anything like an S85.

What is the power potential?

The majority of tuning that will take place for these motors will be bolt on's and basic tuning. This means exhaust and ecu modifications for the most part. The N63 has more room to gain from stock vs. the S63 since it is not in as high of a state of tune also running less boost. Dinan is a notoriously conservative (for street applications) but solid tuner and their gains illustrate this point well. For the N63 Dinan gains about 100 horsepower and 100 pound-feet of torque from the base. On the S63 the gain is only 56 horsepower and 74 pound-feet of torque. This makes sense as boost can not be raised as much with the S63.

Here is an X6 M graph of a before and after tune by OE Tuning. You will see the gains primarily come under the curve down low and the peak HP is not affected all that much. That does not mean the car will not be much faster, area gained is huge but up top at peak there is not as much room to gain as there is with the N63.

What about upgraded turbos?

Yes, oh yes, these will come. Some claim to already have them but we remain skeptical. A tuner named ALSA for example claimed to have upgraded turbos capable of over 700 horsepower for the X6 M. We asked for a dyno graph to substantiate this but never received it. More than one tuner claims such a package but there have not been any real world details to substantiate the claims.

So nobody has done upgraded turbos?

No, Alpina has. The Alpina B7 uses larger turbos on the N63 so clearly it can be done. The thing is, Alpina doing upgraded turbos on an N63 is almost like BMW doing it themselves. The relationship between the two is so close that Alpina can get whatever software support it needs to make the hardware work. This type of work trickles down to other tuners over time but that is the thing, it takes time. So do we believe anyone has a working turbo upgrade package out there yet? Other than Alpina, no, but they will come.

How much power will these motors hit?

I wrote an article in January of last year where I said 700 horsepower will be common place. It will be, as 700 horsepower will not be a number that opens too many eyes on this motor after a while when tuners start hitting it routinely. Even early last year tuners such as Noelle were claiming 650 horsepower out of the N63, let alone the S63. ALSA already is claiming over 700. On the stock internals and fuel system, this is going to be about the limit for the S63. The N63 internals may be hindered slightly by the compression but with big enough turbos even it should approach the 700 mark on the stock internals. There have been no complaints about the fuel system not having enough headroom for this level.

These motors are going to hit big numbers fairly quickly as that is the advantage of having a forced induction motor from the factory. With the S63 being in four M vehicles (X5M, X6M, M5, and M6) at no other time has an M motor been in so many different models at once. Not to mention the number of N63's out there which will benefit from development of the S63. With the proclivity of M owners to seek higher and higher performance and the ease at which forced induction motors are tuned, the tuner competition is going to be intense. Wise tuners would already be working on their offering as hitting quickly to gain control will be vital.

The N63 will be capable of hitting anything the S63 can. With the stock hardware the N63 will not be able to go as far, similar to the difference between a 996 K16 turbo and an X50 K24 996 turbo, but with built internals and larger turbos they both will be able to hit the same eventual peak. One does not have to buy an M motor any longer to be able to have the same type of headroom as an M motor. There is something about that which is bittersweet but it opens BMW tuning to a greater range of people while keeping BMW's own costs down. Not to mention the fuel efficiency gains but we could also argue 555 horsepower 5300 pound SUV's and efficiency are oxymorons.

Any downsides?

Well, not from BMW's perspective. They can take a motor and give it bigger turbos while changing the tuning and call it an M motor. Lowers costs, improves fuel economy, the marketing and accounting departments are happy. For some cars they don't even have to bother with doing anything other than minor software changes (1M coupe). We feel these motors no longer show off the M engineers skill in the same way. They allow them to be lazier as they no longer need to strive for squeezing out every last NA horse. It also allows them to muscle out parts of the tuning market by offering their own software upgrades providing a secondary cash grab. This might force out some of the weaker tuning houses as you all know how BMW owners are weenies when it comes to preserving their warranty. More power and a warranty? For the more restrained/timid crowd it will be an easy choice.

There still is great innovation as the top mount turbos in the V show but the motors are not quite as impressive of an engineering feat or as unique as the naturally aspirated M motors were. These also have a completely different character with a curve that is very unlike what we have grown to expect out of M. Then again, these motors need a ton of torque to move heavy 5300 pound SUV's quickly. Tuning will be different than what we are used to such as trying to add aftermarket forced induction but it looks like there will be more of it and faster. So, there are only downsides depending on your perspective. Many welcome increased torque and easier tuning along with MPG gains, I just wish BMW still gave the customer the choice.

The S63 with its lower compression will be able to handle a TON of boost. 9.3:1 and stouter pistons. if it comes stock at 17.4 psi, I think the turbos are already close to max, 25 psi may be all what you can get which may bring you close to the limit of the turbos.

I think with an exhaust, intake, 25 psi and some meth you should hit the 700s and run low 11s or 10s with slicks and solid launch.

I like the S63 because of its tuning potential, but slapping turbos on a detuned and de-revved S65 is not the solution for BMW M technology.

For every 1000 RPM higher you want the engine to rev, costs another million in development costs. So a low revving turbo motor is a cheap way to lay down numbers.

Dont get me wrong I LOVE my turbochargers, but its not exactly the same technological advancement that the S65 was. So to me, the S63 is taking a step back

I agree and that is why I find the naturally aspirated M motors far more impressive from an engineering standpoint. BMW was able to compete with larger motors and even forced induction motors with just smaller, naturally aspirated powerplants due to how well engineered they were. I find this approach lazier as they don't have to work so hard to maintain the curve up top for rev multiplication.

I honestly do wish they would leave the gas mileage pussy fest for the normal cars and keep the M cars pure the way we all like them, but it's just not possible in this market. At least, the big car companies don't seem to think it's possible.

I honestly do wish they would leave the gas mileage pussy fest for the normal cars and keep the M cars pure the way we all like them, but it's just not possible in this market. At least, the big car companies don't seem to think it's possible.

It's possible, plenty of car companies are still producing NA motors. I think BMW just got greedy selling the change to us under the guise of being green and essentially traded some of their soul for profit.

Honda is a prime example of engine technology coupled with unmatched efficiency. One cannot argue the flagship K20 and F22 with specific outputs exceeding 120 hp per liter. There is still room for technology and impressive engines with efficiency, without having to be a $#@!.

I have a feeling the S63 in the M5 will be different. BMW wouldnt let its flagship car become a slouch up top...its not as heavy as the truck is, but now that it totes the AWD system from a 750 who knows, its getting to be a porker.

BMW could go 2 ways about it. Leave it alone to save money, or listen to its enthusiasts and pump in up in the redline area and match it to the S85.

I have a feeling the S63 in the M5 will be different. BMW wouldnt let its flagship car become a slouch up top...its not as heavy as the truck is, but now that it totes the AWD system from a 750 who knows, its getting to be a porker.

BMW could go 2 ways about it. Leave it alone to save money, or listen to its enthusiasts and pump in up in the redline area and match it to the S85.

I don't think there is any way it can even come close to the s85 curve or top end.

However, we already know it has a higher redline than the X5 or X6 M so some changes have been made. I hope something more than just software.

Awesome article; I have been waiting for something like this for a while! It would be great if you could add a verison number and add appropriate updates, if and when necessary; i.e. as turbo upgrades become available for example. I say this because somebody searching will probably run into this article a year or two from now and may wish for updated info.

Also, in an economy like today's i understand why BMW have chosen financial stability over ingenuity; they just spent a while developing these new engines and they have an inherent ability to be upgraded for better performance, so it is beginning to make sense. NOW, the M3 is where I think M engineers are going to show their magic tricks. I really do think that they are going to be showing us a motor worth its wait, but with porsche doing what they are, it's hard to really match them in terms of 6 cyl FI engines.

Finally, I think the X6M is more of a package than just an engine. The way I see it, especially since I had a modded 335i, is that you have the extra power from the engine, but you need the brakes, engine mounts, handling, differential and such to be able to successfully use the engine. Straight-line power is great, but all that power from a normal bmw really is a testament to why M is different. Package

Awesome article; I have been waiting for something like this for a while! It would be great if you could add a verison number and add appropriate updates, if and when necessary; i.e. as turbo upgrades become available for example. I say this because somebody searching will probably run into this article a year or two from now and may wish for updated info.

Thank you!

The article will pretty much stay as is but when those things come they will receive their own updates. Perpetually updating this to reflect the tuning market won't be feasible, it makes more sense to just update with new articles as things progress. This is a snapshot of where we are as of today.

Originally Posted by alq80

Finally, I think the X6M is more of a package than just an engine. The way I see it, especially since I had a modded 335i, is that you have the extra power from the engine, but you need the brakes, engine mounts, handling, differential and such to be able to successfully use the engine. Straight-line power is great, but all that power from a normal bmw really is a testament to why M is different. Package

Engine mounts and better brakes constitute an M? The X6 M is really about horsepower, not handling. I don't see a radical difference in chassis capability between it and the X6 50i.

The article will pretty much stay as is but when those things come they will receive their own updates. Perpetually updating this to reflect the tuning market won't be feasible, it makes more sense to just update with new articles as things progress. This is a snapshot of where we are as of today.

Engine mounts and better brakes constitute an M? The X6 M is really about horsepower, not handling. I don't see a radical difference in chassis capability between it and the X6 50i.

Really? I would assume that the x6M would be better handling car but if I am wrong, then I guess it is pure horsepower. Do you have numbers for braking distance and skidpad for each? That would be a nice comparison!

Really? I would assume that the x6M would be better handling car but if I am wrong, then I guess it is pure horsepower. Do you have numbers for braking distance and skidpad for each? That would be a nice comparison!

I'm sure the skidpad and braking numbers are slightly better but there is not all that much of a handling improvement that can be done. It isn't like one goes to an LSD and new suspension or anything like that. They still have the same basic AWD system and a 5300 pound curb weight.

I'm sure the skidpad and braking numbers are slightly better but there is not all that much of a handling improvement that can be done. It isn't like one goes to an LSD and new suspension or anything like that. They still have the same basic AWD system and a 5300 pound curb weight.

What really seems to be making it an "M" is the power.

I did not know that; I had assumed what you said is not the case. This is very interesting, and, would make me buy the 50i if that was a decision I was making. Very weird that power is the only difference, to a certain degree.

I did not know that; I had assumed what you said is not the case. This is very interesting, and, would make me buy the 50i if that was a decision I was making. Very weird that power is the only difference, to a certain degree.

To a certain degree the power is the main difference. The brakes are different and they claim to do some different AWD tuning but it's the same basic thing.

Really, the selling point is 555 horsepower. I would definitely opt for the X6 50i.

Honestly X6 M feels way more agile and sharper, I'm sure no one believe me when i say it can challenge sporty cars like CLS55 in handling terms.
But what really is missing in both M SUV's is the feeling, I've never been a fan of AWD/Quattro systems, it makes steering numb and soulless and these SUV's aren't exceptions.

I drove it around, and to be honest it really feels nice. I would love to get my hands on the X5 as its more suited to my/our needs.

Now that you guys mention it, AMG has been all about power....sure they cant handle for $#@! most of the time, but they sure do lay an ass whooping. Its almost like BMW is following in its footsteps...our 'power' cars/trucks cant handle, but we throw a gazillion hp in there and still manage to kick ass anyway.

Now that you guys mention it, AMG has been all about power....sure they cant handle for $#@! most of the time, but they sure do lay an ass whooping. Its almost like BMW is following in its footsteps...our 'power' cars/trucks cant handle, but we throw a gazillion hp in there and still manage to kick ass anyway.